1. Field of the Invention
The present invention relates to a security lighting apparatus of a kind capable of emitting a blinking light (hereinafter referred to as a “flashing light”) within a detection area outside a building such as, for example, a dwelling house or a factory for alert against an intruder, in the event that during the nighttime an unauthorized entry of the intruder into the detection area is detected. More particularly, the present invention relates to optimization of the timing at which the flashing light is triggered on or off.
2. Description of the Prior Art
The security system has been well known, in which in the event that an unauthorized entry of a human being is detected during the nighttime within the detection area outside a building such as, for example, a dwelling house or a factory, a security light is turned on continuously for a predetermined length of time, or a flashing light, i.e., a mode of lighting in which lighting and extinction are cyclically repeated, is triggered at the intruder at late night for alert purpose. By way of example, the Japanese Laid-open Utility Model Publication No. 7-29691 discloses the use of a timer, which is activated in response to detection of an intruder and to switch from the continuous lighting for illumination purpose to the flashing for alert purpose depending on the set-up of the timer. Also, depending on the time period in the nighttime after sunset, the continuous lighting and the flashing can be manually selected one at a time.
With the security lighting apparatus, it is generally considered important to set the timing at which the flashing is initiated at night, depending on change of status of return of a house resident from his or her outing and/or neighboring road conditions. If the flashing starts too early, the flashing intended for the purpose of alert a potential intruder would be unpleasant and/or obnoxious for non-intruders, for example, house residents. On the other hand, if the flashing starts too late, the alert effect of the flashing would not be brought about.
The prior art security lighting apparatus of the kind disclosed in the above mentioned publication is so designed and so constructed that in the event of detection of a human being, the flashing is carried out according to the schedule preset in the timer regardless of whether the human being is an intruder or whether he or she is a non-intruder. Accordingly, where the human being so detected is a non-intruder such as, for example, a house resident, it often occurs that when meeting with the flashing, the non-intruder will feel annoying.
Considering that the hour of sunrise and the hour of sunset vary depending on the season and/or the geographic conditions of the building, the timing at which the flashing is to be initiated generally varies as well. In the case where the security lighting apparatus has a capability of manually selecting one of the continuous lighting and the flashing, setting of the initiating timing at which the security lighting apparatus is activated, i.e., the continuous lighting or the flashing is initiated, based on the length of time passed subsequent to the sunset would require the house resident to ascertain the hour of sunset on a case-by-case basis and, hence, this is indeed complicated and cumbersome.
Also, since the continuous lighting taking place before sunset and the flashing taking place before sunrise serve no purpose since the ambience is light-filled, the initiating timing and the terminating timing have to be properly set and, therefore, complicated and cumbersome procedures are required to accomplish the proper setting of the initiating and terminating timings in consideration of the change required for each season.